A bicyclist was seriously injured Tuesday when he rode into the side of a moving trolley, according to reports.

, shutting down a busy trolley line through part of East County, authorities said.

The man rode around trolley crossing guard arms and hit the trolley around 5:20 p.m. near the Amaya Station, at Amaya and Severin drives, the San Diego Union-Tribune reported. He was knocked to the ground and taken, unconscious with several broken bones to a hospital, a La Mesa police spokesman said.

The trolley line was closed between the Grossmont Center Station and El Cajon Transit Center, and remained shut down until about 9 p.m., according to Rob Schupp of the Metropolitan Transit System.

The tracks there serve the Orange Line between El Cajon and downtown, and the Green Line from Santee to Old Town.

Bus service was arranged as an alternative, Schupp said.